There are a number of sources which you can use at the library. If the house was built after c.1886, the directories will be useful in order to find when the property is first listed  it is likely the house was built just before that year. Prior to 1886, the census returns and maps will help pin down the date, but probably not exactly. For the early nineteenth and eighteenth centuries, there are rate books, but these are less easy to use. Ealing Building Inspection Books, 1906-1979. These name the builder and give exact dates when foundations and other parts of the house were inspected. Extensions and garages are also noted, as are industiral premises. N.B. They only cover those parts of the London Borough of Ealing after they became part of Ealing thus nothing for Hanwell, Greenford and Perivale before 1926; for Northolt before 1928 and for Acton and Southall before 1965.